CVE-2024-42291 is a vulnerability identified in the Linux kernel related to the handling of Flow Director (FDIR) filters in the ice network driver. The vulnerability arises because while the iavf driver enforces a software limit of 128 FDIR filters per Virtual Function (VF), the ice driver lacked a similar enforcement mechanism. This omission allows a malicious VF driver to request more than the intended limit of FDIR filters, potentially exhausting shared resources allocated for other VFs. FDIR filters are used to direct network traffic efficiently by filtering packets at the hardware level, and they consume finite hardware and software resources. By exceeding the filter allocation, a malicious VF can cause resource exhaustion, leading to denial of service (DoS) conditions for other VFs sharing the same physical function. This vulnerability affects Linux kernel versions identified by the commit hash 1f7ea1cd6a3748427512ccc9582e18cd9efea966 and similar builds. The issue was addressed by adding a per-VF limit on the number of FDIR filters in the ice driver, aligning it with the existing limit in the iavf driver. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The vulnerability requires a malicious VF driver to be present, which implies that the attacker must have some level of privileged access or control over a VF in a virtualized environment. This vulnerability is particularly relevant in environments using SR-IOV (Single Root I/O Virtualization) where multiple VFs are assigned to different virtual machines or containers, as it can impact resource isolation and availability among tenants.

For European organizations, especially those operating data centers, cloud services, or virtualized infrastructure using Linux with SR-IOV capable network cards, this vulnerability poses a risk of resource exhaustion leading to denial of service. The exhaustion of FDIR filters by a malicious VF can degrade network performance or cause network outages for other tenants or services sharing the same physical hardware. This can impact service availability, potentially violating service level agreements (SLAs) and causing operational disruptions. Confidentiality and integrity impacts are limited since the vulnerability primarily enables resource exhaustion rather than direct data leakage or manipulation. However, denial of service in multi-tenant environments can indirectly affect business continuity and trust. Organizations in sectors with high reliance on virtualized networking, such as telecommunications, cloud providers, financial services, and critical infrastructure, may face higher operational risks. The absence of known exploits reduces immediate threat but does not eliminate the risk, especially as attackers may develop exploits post-disclosure. The vulnerability also highlights the importance of strict resource management in virtualized network environments to maintain isolation and stability.

1. Apply the latest Linux kernel patches that include the fix for CVE-2024-42291, ensuring the ice driver enforces per-VF FDIR filter limits. 2. Review and update network driver versions and firmware for SR-IOV capable NICs to ensure all relevant fixes are applied. 3. Implement strict access controls to prevent unauthorized deployment or modification of VF drivers by untrusted users or tenants. 4. Monitor VF resource usage actively to detect abnormal spikes in FDIR filter requests that could indicate exploitation attempts. 5. In multi-tenant environments, consider additional isolation mechanisms such as limiting the number of VFs per tenant or using software-based network virtualization alternatives where feasible. 6. Conduct regular security audits of virtualization infrastructure focusing on network resource allocation and driver integrity. 7. Engage with hardware vendors to confirm compatibility and support for updated drivers and firmware addressing this issue. 8. Educate system administrators and security teams about this vulnerability and the importance of patch management in network drivers.